An Erbium-doped fiber laser based on a 3×3 microfiber coupler

A simple and compact Erbium-doped fiber laser is demonstrated with two Sagnac loops formed by a 3×3 microfiber coupler. By fusing two ports on each side of the 3 ×3 microfiber coupler and embedding a 90 cm Erbium-doped fiber in one loop, a stable laser output is achieved at 1530 nm region with an optical signal to noise ratio of ~40 dB using a 980-nm pump. Taking advantage of the large evanescent field and excellent temperature and mechanical properties of the micro-sized coupled area, the device has great potentials in tunable laser and active sensing for refractive index, temperature, strain and pressure.